As the saying goes, "it takes 100 days to get over a serious injury (involved with tendons and bones)." Tendons here also includes muscles.  Convalescing, of course, has a certain effect on the rehabilitation of muscle strains, but invariably doing so can weaken the flexibility and strength of muscle fibers, reduce mobility, or even form nodules and strands, resulting in sequelae of repeated strains.  Therefore, it is best to adapt both active recovery and the combination of dynamic and static methods.